The goal of this project is to test the ability of intra-cortical electrical micro-stimulation to convey useful visual information to subjects. The data obtained from this study will be used to guide the development of a neural vision prosthesis capable of restoring useful visual input in profoundly blind human patients. The Utah Electrode Array, which has 100 micro-electrodes in a 2x4x4 millimeter package, will be used to conduct the proposed experiments, and hopefully will become the corner stone of a neural vision prosthesis. Using subjects'behavioral responses to micro-stimulation of primary visual cortex we will determine: 1) the optimal parameters of micro-stimulation for evoking a visual percept on each electrode in the array, 2) the ability of micro-stimulation on the array to evoke discriminable visual percepts, e.g. one spot of light versus two spots of light, and 3) the ability to evoke more complex patterns of visual percepts using simultaneous micro-stimulation across patterns of electrodes in the array. These experiments will provide a proof-of-concept that patterned electrical micro-stimulation of the visual cortex will evoke subjectively discriminable visual percepts useful for guiding behavior. PUBLIC HEALTH RELEVANCE: There are currently few treatment options available to the profoundly blind. We are developing a vision prosthesis which could potentially restore limited, yet useful vision to the profoundly blind. This vision prosthesis will bypass damage sections of the visual pathways and provide visual input to patients by sending signals from a video camera directly to the vision processing parts of the brain.